Can I use mainland gas for filling up?

04cobra23

04cobra23

Member
Aug 21, 2014
344
Boca Raton Florida
Boat Info
340DA and 215LR
Engines
Twin 8.1's and 4.3 Merc
Morning all. My boat is in a marina getting some work done. Currently gas is $2.25 around town versus $5.00 on the water. I was thinking of putting 150 or so gallons in the boat before she gets wet again. So my question is, is it ok to use mainland gas, if so what octane? It is a 340 with 8.1's.

Thanks!
 
04cobra23 said:
Morning all. My boat is in a marina getting some work done. Currently gas is $2.25 around town versus $5.00 on the water. I was thinking of putting 150 or so gallons in the boat before she gets wet again. So my question is, is it ok to use mainland gas, if so what octane? It is a 340 with 8.1's.

Thanks!
Click to expand...

If you can get Non Ethanol I think it is called Rec 90 in Fla I would do it. If it is ethanol I would not
 
Sure. 87 octane is fine. Don't stress too much about ethanol, or not - just make sure you use the proper additive such as Startron. And don't be shy with it - you can't overdose. Check with the marina to be sure you are allowed to do this.
 
Checked with them, they do not have fuel docks so its ok. I checked on that site and there is a couple around me that have rec-90. It's roughly 4.00 a gallon.
 
The only thing that a higher octane will do for you (and that engine) is take more money out of your pocket. The engine will not run any better nor will it get better fuel economy. The gas will last longer at the required octane, but Startron (and others) does that, too. It would be a waste to buy higher octane.

Yes, that's the stuff - but find it in the 32oz bottle. Should be under $30 and that treats 16 gallons for every 1 ounce. Actually, if you can find the diesel version of Startron, you can buy that. It's only slightly more expensive, but it treats 32 gallons per ounce.
 
If the fuel is to be burned and not sit in the tank for an extended period of time ... Why would it be necessary to include additives?
 
I have used street gas (87 Octane) for years. There is no non-ethanol gas where I live. I only add stabol at when winterizing. If you use your boat frequently the gas gets burned before you will have problems with ethanol. There is no real advantage to pay for mid grade or 93 Octane. Unless you let your boat sit for all periods without use (Octane will drop with time). High Octane prevents eary ignition of fumes under pressure, and is only needed for high compression engines and engines with turbos. Our boats run fine on regular gas...
 
jgarko said:
If the fuel is to be burned and not sit in the tank for an extended period of time ... Why would it be necessary to include additives?
Click to expand...

IF you are POSITIVE that it will get burned relatively quickly, then you wouldn't need the additive from a stabilizer viewpoint. But there are still benefits to using it as it's supposed to help keep fuel systems (carbs, fuel injectors) clean, preventing phase separation, etc. That part could probably be debated, but for me, I'd rather just pay the 5 cents extra per gallon and play it safe. To me, that's pretty cheap insurance.

Be careful not to compare boat use to car use. There are other variables involved in boating that we don't run into with cars.
 
Thanks everyone. I am going to make a few trips and fill the tanks before I launch the boat. I'll take advantage of saving a few hundred bucks.
 
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